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INVENTORl N4 PETERS. PHOTO LITHOQRAPH WAQHINmoN D C WITNESSESI SJW/. z SIMM.

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N. PETERS. PHOTO-Ll MOGRAPHER WASHINGTON D C ITED STATES PATENT OFFICE.

H. D. J. PRATT, OF VASHING'IAON, DISTRICT OF COLUMBIA.

MARINE PROPELLER.

Specification of Letters Patent No. 30,757, dated November 27, 1860.

To all whom tt may concern:

Be it known that I, H. D. J. PRATT, of the city of Washington, in the District of Columbia, have invented certain new and useful Improvements in Apparatus for Pro pelling Vessels; and I do hereby declare the following to be a correct description of the same, reference being had to the accompanying drawings, in which- Figure l, is a side elevation of my improved propelling apparatus; Fig. 2, is a longitudinal central section of the same; Fig. 3, is a side elevation of a form adapted for use at bow or stern of vessel; Fig. 4, is a longitudinal section of the same; Fig. 5 is a bottom view of the propeller cut water; Fig. 6, is a central transverse section of the same; Fig. 7 is an end view showing the circular butt in which the propeller shaft rests; Fig. 8 is a side elevation of the propeller cutwater.

The object of my invention is to facilitate the use of a long cylindrical propeller, ap'- plied either to the bottom of the vessel or on either side of the keel, by providing, in a cut water of peculiar form, such a means of receiving and delivering the water to the propeller, and of dismissing it after it has been acted upon by the blades as will create the least disturbance of its density, and consequently of its resisting power; and further by making the cylinder and wings hollow so far as not to interfere with their strength and yet so as to diminish objectionable weight and friction on the journals, thus increasing the effective power of the motor that may be employed to drive the propeller. And my invention further consists in the use of stationary `vanes arranged in such positions in relation to the propeller as to diminish the breaking up and escape of the water from the action of the blades, and thus prevent much of the loss of power that ordinarily results from that cause.

In the drawings the same letter marks the same part wherever it occurs.

A marks the cut water at the forward or entering end of the propeller, and B the corresponding piece, or heel as I term it, at the after end of the propeller. These parts are sharp at a and ZJ, and have their greatest thickness at about the middle of their length. They are made hollow both for the sake of lightness and buoyancy and also for the purpose of affording facilities for connecting the propeller to the driving wings or vanes of the propeller. Various modes of connecting the cylinder C to the butt E may be adopted. Thus, instead of two flat surfaces coming together as in the drawing, the end of the cylinder may be made conical and be received into a cavity of corr-esponding form in the butt, or vice versa. The propeller vanes I propose to make hollow, when preferred, and in some cases, to make them, at the middle of the length of the cylinder, broad at the base and taper them toward both ends of the cylinder till their edges are thin and sharp at the entering and leaving points. They may also have a flange upon their outer rim to increase their strength, and to assist in pre venting the escape of the water.

The model of the cutwater A and heel B is to be varied to correspond with the general character of the model of the vessel to which they are attached, and according to the particular position which the propeller is to occupy, as long as the principle of form here indicated is not departed from.

To increase the resisting power of the water by preventing its slipping away from the propeller, I make use of stationary vanes I, parallel with the axis of the propeller, and attached to the side or bottom of the vessel. Any desired number may be used, and they should project far enough to reach nearly to the rim of the propeller. Their edges may be straight, curved or corrugated to correspond with the rim of the propeller, and they may be placed at its ends as well as sides, as seen in Fig. 4. In pursuance of the same principle, I propose to surround the propeller in whole, or in part, with a cylinder IQ as seen in Figs. 3 and 4, and to provide the interior of said cylinder with vanes I arranged either longitudinally or spirally within it.

The propeller may be used either at the bow or stern of the vessel. In either case a modification of the arrangement, such as is 2. In combination With a propeller hung and operated as described, the stationary vanes I, Whether placed on the sides or Ybotl tom of the vessel, or at one or 'both ends o'f the propeller, or Within a cylinder surrounding it, as and for the purpose specied.

3. Giving to the edges of the stationary vanes, an undulating form, the prominences of which pass Vbetween prominences of corresponding form on the edges of the propeller vanes, as shown.

The "above specification signed and Witnessed this 26th day of May A. D. 1860.

s H. vD. J. PRATT.

Witnesses:

CHAS. F. STANSBURY,

EDM. F. BROWN.V 

